Apparatus for applying pressure sensitive adhesive to glass fiber mesh material

ABSTRACT

Adhesive coating equipment having an adhesive reservoir heated by circulating electrically heated oil. A first lower hollow roller is mounted above the reservoir having a lower portion immersed in the adhesive contained in the reservoir. A power driven second hollow top roller is mounted above and in contact with the first roller and rotates the first roller transferring adhesive from the reservoir to the first roller and then to the top roller for coating a web passing over the top of the second roller. The rollers are heated by heated oil circulated through the interior of the rollers to maintain the rollers and adhesive at the same temperature and the adhesive at the same viscosity throughout the transfer of adhesive from the reservoir to the web. An idler roller is located adjacent to the lower and top rollers for maintaining at least a predetermined minimum arcuate length of web contact with the second or top roller. A method of applying pressure sensitive adhesive to glass fiber mesh material by passing the mesh material over a heated rotating coating roller. Heated adhesive is applied to the coating roller which is transferred to the mesh material by contact with the roller as the mesh passes over the roller. The length or duration of contact of the mesh material with the coating roller is controlled so that a uniform amount of adhesive is applied to the mesh material. The mesh material is maintained under constant tension as it is payed out from a supply roll and over the coating roller to a collection roll.

Carpenter et a1.

[ APPARATUS FOR APPLYING PRESSURE SENSITIVE ADHESIVE TO GLASS FIBER MESH MATERIAL [75] Inventors: Guy H. Carpenter, Dover; Ernest E.

Ross, Dennison, both of Ohio [73] Assignee: Perma Glas-Mesh Corporation,

Dover, Ohio [22] Filed: Apr. 14, 1971 [21] App1.No.: 133,982

[52] U.S Cl 118/33, 118/202, 118/235,

[51] Int. Cl. B05c l/l2 [58] Field of Search 118/202, 33, 246, 262, 235

[56] References Cited UNITED STATES PATENTS 1,049,139 12/1912 Owens 118/246 X 3,647,525 3/1972 Dahlgren 118/246 X 2,678,284 5/1954 Holt 118/202 X 1,961,827 6/1934 Rutkoskie 118/202 1,170,520 2/1916 Erickson et al 118/262 X 3,279,425 10/1966 Gottscho 118/202 1,476,988 12/1923 Latta 118/202 X 1,618,799 2/1927 Blum 118/202 X 2,774,684 12/1956 Fucinari 118/202 X 3,070,457 12/1962 Labombarde 118/202 X Primary ExaminerJohn P. McIntosh Attorney, Agent, or FirmFrease & Bishop [4 Jan. 29, 1974 5 7 ABSTRACT Adhesive coating equipment having an adhesive reservoir heated by circulating electrically heated oil. A first lower hollow roller is mounted above the reservoir having a lower portion immersed in the adhesive contained in the reservoir. A power driven second hollow top roller is mounted above and in contact with the first roller and rotates the first roller transferring adhesive from the reservoir to the first roller and then to the top roller for coating a web passing over the top of the second roller. The rollers are heated by heated oil circulated through the interior of the rollers to maintain the rollers and adhesive at the same temperature and the adhesive at the same viscosity throughout the transfer of adhesive from the reservoir to the web. An idler roller is located adjacent to the lower and top rollers for maintaining at least a predetermined minimum arcuate length of web contact with the second or top roller.

A method of applying pressure sensitive adhesive to glass fiber mesh material by passing the mesh material over a heated rotating coating roller. Heated adhesive is applied to the coating roller which is transferred to the mesh material by contact with the roller as the mesh passes over the roller. The length or duration of contact of the mesh material with the coating roller is controlled so that a uniform amount of adhesive is applied to the mesh material. The mesh material is maintained under constant tension as it is payed out from a supply roll and over the coating roller to a collection roll.

4 Claims, 5 Drawing Figures INVENTORS GUY H CARPENTER ERNEST E. ROSS ATTOR NEYS PATENTEB JAN 2 9 I974 sum 1 0f 2 PATENIEB 3.788.271

4 NVENTORS.

GUY H.CARPENTER ERNEST E. ROSS ATTORNEYS material being coated,

APPARATUS FOR APPLYING PRESSURE SENSITIVE ADHESIVE TO GLASS FIBER MESH MATERIAL BACKGROUND OF THE INVENTION 1. Field of the Invention The invention relates to equipment for applying a coating of liquid material to a roll of mesh material. More particularly the invention relates to equipment for applying pressure sensitive adhesive to glass fiber mesh material in uniform controlled amounts largely to one side of the material.

2. Description of the Prior Art Many types of coating equipment and methods have been used to apply coatings of various kinds to a variety of materials. The applied coating may be protective such as tar, paint, or the like. It may be a stiffening agent such as latex or starches; or may be an adhesive such as those applied to surgical tapes and first aid bandages. These various coatings may be applied to one or both sides of the material or to portions thereof, depending upon the type of coating used; the type of and the intended use of the coated material.

Prior equipment and methods typically used for coating various materials have consisted generally of a series of rollers such as shown in U.S. Pat. Nos. 2,349,709; 3,265,034 and 3,391,037 over or between which the material to be coated is passed. The coating material is transferred by rollers from a supply tank in liquid form to a main coating roller for transfer to a moving web to be coated, or else sprayed from stationary supply fountains or spray nozzles onto the moving web.

Other known equipment and methods pass the material to be coated directly through a tank containing the coating material which coats the material on both sides. The coated material then is passed between squeeze rollers to remove excess coating material.

The prior art equipment and methods have proven satisfactory for coating operations where accurate control of the amounts of coating applied or accurate control of the coating temperature or accurate control of the location of the coating on the material is not necessary. However, in applying pressure sensitive adhesive mainly to one side ofa glass fiber mesh material, greater control is required than is practical with prior equipment and procedures of the temperature and viscosity ofthe liquid adhesive, and of the amount of time and of surface contact existing while the liquid adhesive is applied to glass mesh.

Known adhesive coating equipment, in which the material is coated by contact with the top portion of an adhesive coated rotating coating roller as the material travels from a supply roller to a collection roller, has the disadvantage that the material being coated does not maintain the same length of contact with the coating roller due to the increasing size of the collection roller on which the coated material accumulates. The dimension of this contact are during which the adhesive is transferred from the coating roller to the material is critical to accurate adhesive application since the greater the minimum arc of contact, the greater the amount of adhesive transferred to the material and vice versa.

The adhesive generally is supplied to such transfer rollers from a heated reservoir or spray fountain in which the adhesive is maintained at a specific temperature level to achieve the desired adhesive viscosity.

Problems arise, however, in that the temperature of the adhesive rapidly decreases as it moves from the reservoir between transfer rollers, and the temperature drop results in loss of desired viscosity when the coating is applied to the moving web. Likewise; the adhesive tends to build up on the rollers when its temperature drops, thereby affecting the coating efficiency.

Difficulties have arisen with prior coating equipment using heated oil in closed tanks to melt or heat the particular coating material in that hot spots" develop in the oil reservoir adjacent the heat supply. These hot spots create uneven heating of the coating material, which when transferred to the contact roller results in uneven material temperatures on the roller which in turn results in an uneven coating applied to the moving web. Also, as the oil temperature changes, the pressure within prior closed tanks change making accurate control of the oil and heated adhesive temperatures difficult to maintain.

No adhesive coating equipment or method of which we are aware has eliminated the problems of applying a uniform amount of pressure sensitive adhesive largely to one side of a moving web of material to be coated by maintaining a minimum length of contact arc between the material and adhesive transfer coating roller, and by maintaining the adhesive coating at a predetermined temperature throughout the coating process.

SUMMARY OF THE INVENTION Objectives of the invention include providing equipment for applying pressure sensitive adhesive to glass fiber mesh material in which the viscosity and temperature of the adhesive is controlled and maintained constant until after the web is coated; providing equipment for applying a pressure sensitive adhesive to glass fiber mesh material in which the adhesive transfer or coating roller contact with the moving web is maintained with predetermined minimum arcuate length regardless of the amount of mesh material on the supply and collecting rolls; providing equipment for applying pressure sensitive adhesive to glass fiber mesh material which requires little or no adjustment during the coating operation, which provides uniform tension on the web throughout the coating operation which enables the web to be payed out directly and conveniently from supply rolls of the mesh material and to be rewound on similar rolls after the coating has been applied, for easy handling, storage and shipment; providing equipment for applying pressure sensitive adhesive to glass fiber mesh material in which the quantity of adhesive applied to the web is controlled so that a much greater quantity of adhesive is applied to one side of the web than to the other side in order that the web has sufficient adhesive to adhere to an object, yet does not adhere to adjacent laps in a roll of coated material to such extent as to prevent easy separation therefrom; providing a new method for applying pressure sensitive adhesive to glass fiber mesh material; and providing new equipment and procedures eliminating numerous difficulties heretofore encountered, achieving the objectives simply, effectively and inexpensively, and solving problems and satisfying existing needs.

These objectives and advantages are obtained by the equipment for applying pressure sensitive adhesive to glass fiber mesh material the general nature of which may be stated as including in coating equipment for coating a web of material moving between a supply roll and a collection roll; guide and tension means for paying out the web from the supply roll; a coating material supply reservoir; a first roller mounted on a horizontal axis above the reservoir and partly submerged in the coating material contained therein; a second or coating roller adjustably mounted above and aligned with its axis parallel to the first roller over which the web to be coated is passed and in contact with a portion of said second roller; means for positively driving the second roller which in turn frictionally drives the first roller by contact therewith whereby coating material is transferred from the reservoir to the first roller, then to the second roller and then is deposited on the moving web from the second roller; means for heating the coating material contained in the reservoir and the first and second rollers to maintain all at the same temperature preferably in the range of 400 F. to 450 F. when using a Hot Melt LHM 922 adhesive; and a third roller spaced from the second roller with its axis in parallel alignment with the second roller and located below the level of the second roller web contact portion whereby the web contact portion may be maintained above a predetermined minimum value as the size of the collection roll varies.

Preferred embodiments of the equipment of the invention illustrative of the best modes in which applicants have contemplated applying the principles are set forth in the following description and shown in the drawings, and are particularly and distinctly pointed out and set forth in the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS the arrows 2-2, FIG. 1, showing the circulating oil I heating system;

FIG. 3 is a sectional view, with portions broken away, looking in the direction of the arrows 3-3, FIG. 1; and

FIG. '4 is an enlarged sectional view taken on line 44, FIG. 3, showing the adhesive being applied to the moving web of mesh material.

Similar numerals refer to similar parts throughout the drawings.

DESCRlPTlON OF THE PREFERRED EMBODIMENT Referring to HQ 1, a roll of glass fiber mesh material 1 is mounted on reel 2 and the web 3 is payed out over guide rollers 4 and 5 and under tension rollers 6 and 7, moving in the direction indicated by arrows A. Web 3 then moves over the improved coating roll means equipment indicated at 8 which applies a coat of pressure sensitive adhesive to the underside surface of web 3. The coated web then is collected or rewound as a roll 9 on a take-up reel 10.

One example of glass fiber mesh material preferably has ten threads in the warp and ten threads in the fill for each inch of material. The individual mesh threads are extremely pliable and the mesh in roll 1 preferably has been pretreated with a skin coat of liquid latex or similar stiffening agent applied by any usual coating process.

A series of endless drive chains 11 are driven by a motor 12 through a gear reduction box 13 to provide interconnected positive driving power to guide rollers 4 and 5, coating equipment 8, and takeup reel 10. Interconnected drive chains 11 maintain the speed of moving web 3 constant at all locations, thus maintaining a constant tension on web 3 preventing it from binding or piling up along its travel path.

Reel 10 preferably includes a slip clutch operatively connected to an air line 14 to maintain the peripheral speed of the roll 9 of coated material constant and at the same speed as that of web 3 as the diameter of roll 9 increases. An adjustment valve and air gauge 15 is connected in air line 14 to adjust and regulate the reel 10. Likewise, an air brake may be connected to reel 2 to prevent over running of roll 1 during paying out of web 3.

In accordance with the invention, the coating means 8 (FIGS. 2 and 3) includes a double compartment tank or reservoir 16 having a closed bottom compartment 17 and an open top compartment 18. Bottom compartment 17 is filled with oil 19 which is heated in order to melt adhesive 20 contained in top reservoir compartment 18.

An adhesive 20, which we have found to provide a satisfactory pressure sensitive coating on glass fiber mesh material may be a hot melt type adhesive sold by Stein Hall & Company, lnc., of 605 Third Avenue, New York, N.Y., l00l6, and identified as its .l-lot Melt LHM-922 product. This material is a solid at room temperature and has a melting point of approximately 325 F.

The adhesive should have a uniform temperature in the range of from 400 F to 450 F. while carrying out the coating procedure. This temperature may vary somewhat depending upon the batch of material obtained from the supplier. For example, some batches of the Hot Melt LHM-922 material provided a satisfactory coating when maintained at 400 F. during the coating operation. However, other batches initially had to be heated to 475 F., and maintained at that temperature for l to 2 hours in order to provide a satisfactory coating. The temperature was finally stabilized at not less than 425 F., and preferably between 425 F. and 450 F. with such batches of adhesive.

We have discovered further that the higher the temperature of the adhesive 20, the more fluid is the mate rial; and that the more fluid the adhesive 20 is, the easier it is to control the desired amount of coating transferred to the moving web.

Accordingly, using Hot Melt LHM-922 adhesive, the coating temperature should be maintained at a uniform temperature in the range of 400 F. to 450 F.

A hollow transfer roller 21 preferably is made of steel and is rotatably mounted longitudinally above tank 16 with a lower portion thereof extending into top compartment 18 for partial submersion in adhesive 20. A hollow coating roller 22 is mounted with its axis parallel to and above transfer roller 21 and in contact therewith. Coating roller 22 is driven by chains 11 in a clockwise direction, indicated by arrow B, and imparts a counterclockwise directional rotation, arrow C, to bottom roller 21 which is freely mounted without positive drive means connected thereto. Roller 22 is adjustable vertically with respect to roller 21 to permit change in the contact pressure between the two rollers,

the purpose of which is explained below.

An idler or control roller 23 is located on the upstream side of rollers 21 and 22, parallel with rollers 21 and 22 and positioned below the top portion of roller 22. Web 3 upon passing beneath roller 23 rotates it in .a counterclockwise direction, indicated by arrow E and approaches roller 22 in an upward direction, as best shown in FIG. 4.

Oil 19 in compartment 17 is heated by a number of heating elements, preferably electric resistance heaters 24 (FIG. 3) which extend through a wall 25 of tank 16 into compartment 17. The outer ends of heaters 24 are connected in junction boxes 26 to a power supply line 27 which connects to a source of electric power.

Oil 19 is pumped from compartment 18 through line 28 by a pump 29, then through branch lines 30 and 31 into and through rollers 21 and 22, respectively, and back into compartment 17 through line 32. The circulating oil is not under pressure but flows freely to prevent hot spots" from being formed within the oil and adhesive, and raises the surface temperature of rollers 21 and 22 to the same temperature as heated adhesive 20 within tank 16. This enables adhesive 20 carried by rollers 21 and 22 to maintain the desired temperature and viscosity until applied to passing web 3 and eliminates buildup of adhesive on the rollers.

A third oil line 33 is connected between compartment 17 and a standpipe 34. Standpipe 34 is maintained partially filled with oil 19 through top 35 which is open to the surrounding atmosphere. Thus the oil level within open standpipe 34 changes as the oil temperature within compartment 17 changes due to the heating and cooling of oil 19 and the pumping action of pump 29 used to maintain a constant flow of oil within compartment 17 to enable accurate temperature control of adhesive 20 at the time of transfer to the moving web.

A drain line 36 may be connected to the top of standpipe 34 to drain off any oil should the oil level rise therein.

The operation of rollers 21, 22 and 23 is shown diagrammatically in FIG. 4. Web 3 passes beneath idler roller 23 and over coating roller 22 continuing downwardly directly toward takeup reel 10 without being acted upon or contacting other equipment, such as control and tensioning rollers, dusting chambers, etc. as is shown in FIG. 1. Web 3 contacts roller 22 throughout an arc length, indicated at D, as it passes over roller 22. The length of arc D depends upon the angles of approach and departure of web 3 with respect to roller 22.

The length of are D should remain as nearly constant as possible throughout the coating operation and at least must have a minimum length of 3 inches to insure a uniform coating of adhesive on the moving web 3. With a 3-inch arcuate length of contact of roller 22 with web 3, substantially all of the thin coat 38 of adhesive on coating roller 22 is transferred to the undersurface of web 3.

In accordance with the invention, the length of arc (1,, which remains constant regardless of the size of the roll 9 of coated material shown by the dot-dash line 40 in FIG. 1, should be at least 3 inches for 10 X 10 mesh fabric. Variation in the outer diameter 40 of the roll of coated material will change the length of the arc d However, since arc d is considerably smaller than arc d,, the total length of web contact indicated by the are D is not appreciably affected by the change in the size 40 of the roll 9 of coated material. As clearly shown in FIGS. 1 and 4, the axis of reel 10 is located sufficiently below the axis of coating roller 22 so that the periphery of roll 9 always is lower than the top of roller 22.

It appears that with a minimum length of coating roll contact, measured by the length of arc d of 3 inches, substantially all of the adhesive 38 is transferred to the moving web during such 3 inches of contact, and the changing length of arc d does not appreciably affect the uniformity of the coating applied to the moving web 3 since there is little coating remaining on coating roll 22 after there has been 3 inches of contact measured by the are (1,.

Roller 21 is rotated in a counterclockwise direction by contact with roller 22 and picks up a quantity of heated liquid adhesive 20 indicated at 37, from top compartment 18 and transfers a thin coat of adhesive indicated at 38 to roller 22. A layer 39 of adhesive 20 of predetermined thickness thus is applied to the underside surface of web 3 as it moves over roller 22 throughout are D and then in a downward direction directly to takeup reel 10, as illustrated in FIG. 1. The thickness of adhesive coat 38 formed on roller 22 is controlled easily by vertically adjusting the position of roller 22. Changing the pressure between rollers 21 and 22 permits more or less adhesive to be transferred between rollers 21 and 22 and likewise between roller 22 and web 3.

Therefore, the desired adhesive layer thickness 39 applied to web 3 is controlled and regulated easily by maintaining uniform temperature and viscosity of adhesive 20 and a predetermined minimum contact length of arc d.

An idler roller similar to roller 23 may be placed downstream from rollers 21 and 22 in a location generally opposite that of roller 23 to maintain a constant length of are D regardless of change in size of the roll 9 of coated mesh.

Difficulties may arise however in using a control roll downstream of coating roll 22 when coating open mesh material, in that small quantities of adhesive 20 may seep through web 3 onto the top web surface eventually building up on an idler control roller. Thus it has been discovered that a control roller 23 functions most satisfactorily when placed upstream of rollers 21 and 22 as shown in FIGS. 1 and 4.

We have discovered further, using the stated Hot Melt LI-IM-922 adhesive, maintained at a uniform temperature during coating in the range of from 400 F. to 450 F., with a minimum 3 inch length of contact with the coating roll of the moving web of 10 X 10 mesh glass fiber mesh material, the web speed is preferably maintained at 30 feet per minute.

Accordingly, the present invention provides new and improved equipment for applying pressure sensitive adhesive to a glass fiber mesh material which maintains the adhesive temperature and viscosity at a uniform level throughout the coating step by circulating heated oil through the coating and transfer rollers; provides means for maintaining the oil supply level and oil flow constant within the circulating oil system; provides for a predetermined minimum length of contact are between the moving web and coating roller regardless of the changing size of the rewound roll of coated material; provides for easily adjusting the thickness of the adhesive layer applied to the moving web; provides a new procedure for applying pressure sensitive adhesive to a glass fiber mesh material; and provides improved equipment and methods eliminating difficulties encountered with prior equipment and methods, achieving the objectives and solving problems existing in the art.

In the foregoing description, certain terms have been used for brevity, clearness and understanding but no unnecessary limitations are to be implied therefrom beyond the requirements of the prior art, because such terms are used for descriptive purposes and are intended to be broadly construed.

Moreover, the description and illustration of the invention is by way of example, and the scope of the invention is not limited to the exact details of construction shown or described.

Having now described the features, discoveries and principles of the invention, the manner in which pressure sensitive adhesive is applied to a glass fiber mesh material, and the manner in which the improved equipment by which the adhesive is applied is constructed, assembled and operated, the characteristics of the new construction, and the advantageous, new and useful results obtained; the new and useful structures, devices, elements, arrangements, parts, combinations and methods are set forth in the appended claims.

We claim:

1. In coating equipment for coating hot, fluid, pressure sensitive adhesive primarily on one surface of glass fiber mesh material of a type in which a web of such fiber mesh material is payed out from a supply roll of such material, then is passed under tension over a driven coating roller journalled on a horizontal axis, then passes in a downward direction from the top of the coating roller directly to a windup reel, and then is rewound on the windup reel in roll form; the combination of coating-material-containing reservoir means; a first roller mounted on a horizontal axis below and contacting and driven by the coating roller and partially submerged in hot fluid coating material in the reservoir for transferring hot fluid coating material from the reservoir to the coating roller; means for adjusting the location of the axis of the coating roller with respect to the first roller to control the amount of hot fluid adhesive transferred from the reservoir to the coating roller and coated on the web; means for heating the coating roller and first roller and the coating material to a predetermined hot fluid temperature and maintaining the roller and coating material at the same uniform temperature; control roller means under which the web is engaged and from which the web passes upwardly to the coating roller; said control roller means being located upstream of the coating roller and spaced from and having its axis located below and parallel with the axis of the coating roller to maintain a predetermined minimum length of arcuate contact of the web with the coating roller as the web passes upwards and over the coating roller; said roller arcuate contact length extending at least from the top of said coating roller a predetermined distance along said roller in the upstream direction; the windup reel being located downstream of the coating roller with respect to the direction of web movement and spaced from and having its axis located below and parallel with the axis of the coating roller; the axis of said windup reel being located with respect to the axis of the coating roller that the periphery of the rewound roll of coated web material always is below the top of thee coating roller; and said space between the coating roller and windup reel being free of equipment in contact with the coated traveling web, whereby the web after passing over the coating roller moves downwardly directly to said windup reel and collects in roll form thereon.

2. The construction defined in claim 1 in which the reservoir means includes walls forming an open top compartment and'a separate confined bottom compartment; in which the coating material is contained in the open top compartment; in which the bottom compartment is filled with heat transfer fluid; in which means is provided for heating the fluid in the bottom compartment; in which the first and coating rollers are hollow; and in which conduit means is provided for circulating heated fluid between the hollow rollers and the bottom compartment to maintain the rollers and coating material at the same temperature.

3. The construction defined in claim 2 in which the conduit means connects the bottom compartment and each of the hollow rollers; in which pump means communicates with the conduit means for circulating the fluid between the hollow rollers and bottom compartment; and in which standpipe means open to the atmosphere communicates with said conduit means to eliminate pressure buildup during circulation of the fluid between the bottom compartment and hollow rollers.

4. The construction defined in claim 1 in which the coating material is pressure sensitive adhesive material; and in which means is provided to maintain the adhesive coating material and rollers at a temperature between 400 F. and 450 F during coating. 

1. In coating equipment for coating hot, fluid, pressure sensitive adhesive primarily on one surface of glass fiber mesh material of a type in which a web of such fiber mesh material is payed out from a supply roll of such material, then is passed under tension over a driven coating roller journalled on a horizontal axis, then passes in a downward direction from the top of the coating roller directly to a windup reel, and then is rewound on the windup reel in roll form; the combination of coating-material-containing reservoir means; a first roller mounted on a horizontal axis below and contacting and driven by the coating roller and partially submerged in hot fluid coating material in the reservoir for transferring hot fluid coating material from the reservoir to the coating roller; means for adjusting the location of the axis of the coating roller with respect to the first roller to control the amount of hot fluid adhesive transferred from the reservoir to the coating roller and coated on the web; means for heating the coating roller and first roller and the coating material to a predetermined hot fluid temperature and maintaining the roller and coating material at the same uniform temperature; control roller means under which the web is engaged and from which the web passes upwardly to the coating roller; said control roller means being located upstream of the coating roller and spaced from and having its axis located below and parallel with the axis of the coating roller to maintain a predetermined minimum length of arcuate contact of the web with the coating roller as the web passes upwards and over the coating roller; said roller arcuate contact length extending at least from the top of said coating roller a predetermined distance along said roller in the upstream direction; the windup reel being located downstream of the coating roller with respect to the direction of web movement and spaced from and having its axis located below and parallel with the axis of the coating roller; the axis of said windup reel being located with respect to the axis of the coating roller that the periphery of the rewound roll of coated web material always is below the top of thee coating roller; and said space between the coating roller and windup reel being free of equipment in contact with the coated traveling web, whereby the web after passing over the coating roller moves downwardly directly to said windup reel and collects in roll form thereon.
 2. The construction defined in claim 1 in which the reservoir means includes walls forming an open top compartment and a separate confined bottom compartment; in which the coating material is contained in the open top compartment; in which the bottom compartment is filled with heat transfer fluid; in which means is provided for heating the fluid in the bottom compartment; in which the first and coating rollers are hollow; and in which conduit means is provided for circulating heated fluid between the hollow rollers and the bottom compartment to maintain the rollers and coating material at the same temperature.
 3. The construction defined in claim 2 in which the conduit means connects the bottom compartment and each of the hollow rollers; in which pump means communicates with the conduit means for circulating the fluid between the hollow rollers and bottom compartment; and in which standpipe means open to the atmosphere communicates with said conduit means to eliminate pressure buildup during circulation of the fluid between the bottom compartment and hollow rollers.
 4. The construction defined in claim 1 in which the coating material is pressure sensitive adhesive material; and in which means is provided to maintain the adhesive coating material and rollers at a temperature between 400* F. and 450* F. duRing coating. 